A conventional terminal device is generally provided with a front-facing camera and a rear-facing camera that are used to capture images. The front-facing camera, also referred to as a secondary camera, is disposed on a front surface (for example, a side with a display screen) of the terminal device, and has relatively poor performance. The rear-facing camera, also referred to as a primary camera, is disposed on a rear surface of the terminal device, has relatively good performance, and is an image capture unit more frequently used.
In recent years, a terminal device provided with only one rotatable camera is invented. The camera is rotatable relative to the terminal device. When in a front-facing state, the camera is used as a front-facing camera, and when in a rear-facing state, the camera is used as a rear-facing camera. After the camera finishes capturing an image, a processor needs to determine whether the camera is in a front-facing state or a rear-facing state. Because when the camera is rotated to be in a front-facing state, a control unit needs to give an instruction of rotating the image 180°. An upright image can be output only in this way.
Therefore, it is very necessary for the terminal device to determine whether the rotatable camera is in a front-facing state or a rear-facing state. However, the rotatable camera disposed on the terminal device occupies partial structure space of the terminal device. Moreover, there is a tendency of making the terminal device ultrathin in recent years. As a result, the structure space of the terminal device is further reduced. In this case, how to dispose an apparatus used to identify a state of the rotatable camera in limited structure space becomes a problem for designers.